code: def data_datetime(self):
      data = pd.DataFrame(
          {
              "attr_datetime": np.array(
                  [
                      "2014-10-31 14:13:01",
                      "2004-03-13 19:49:31",
                      "1998-12-06 09:10:11",
                  ],
                  dtype="datetime64",
              )
          }
      )
      return data, "test_datetime", EXPECTED_DATETIME.copy()
  
file_path: scikit-survival/tests/test_io.py
imports: from collections import OrderedDict
  from io import StringIO
  import numpy
  import pandas
  import pandas.testing
  import pytest
  from sksurv.io import loadarff, writearff
  from sksurv.testing import FixtureParameterFactory
label_desc: Use image node_id 6 for calling the DataFrameCases obj's underlying member method code with example usage: obj.data_datetime() and returns: data,  str,  EXPECTED_DATETIME